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1、International Standard ) 8391/ 1 0 a 4 4g!ib INTERNATIONAL ORGANIZATION FOR STANDARDIZATION.MEAYHAPOAHAR OPrAHM3AUHR llOCTAHAAPTbi3AUW.ORGANlSATlON INTERNATIONALE DE NORMALISATION Ceramic cookware in contact with food - Release of lead and cadmium - Part 1 : Method of test Articles de cuisson en dra
2、mique en contact avec /es aliments - Emission de plomb et de cadmium - Partie 1: Mkthode d essai First edition - 1986-12-01 iii n UDC 642.72 : 666.5 : 614.3 Ref. No. IS0 8391/l-1986 (E) -_ 7 Descriptors : food-container contact, ceramics, kitchen utensils, tests, determination of content, soluble ma
3、tter, lead, cadmium. i - Price based on 4 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 21:54:21 MDTNo reproduction or networking permitted without license from IHS -,-,-
4、 Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a
5、technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the membe
6、r bodies for approval before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting. International Standard IS0 6391 /I was prepared by Technical Committee ISO/TC 166, Ceramic wa
7、re, glassware and glass ceramic ware in contact with food. Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. 0 International Organization fo
8、r Standardization, 1986 l Printed in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 21:54:21 MDTNo reproduction or networking permitted without license from IHS -,-,
9、- INTERNATIONAL STANDARD IS0 8391/l-1986 (El Ceramic cookware in contact with food - Release of lead and cadmium - Part 1 : Method of test 0 Introduction The problems of lead and cadmium release from cookware require effective means of control to ensure the protection of the population against a pos
10、sible health hazard. This potential arises when improperly formulated, applied or fired glazes are applied to cookware. There is a particular concern for cookware because the normal conditions of use (heating acid foods for prolonged periods) are conducive to the extraction of soluble lead and cadmi
11、um into food. As a secondary consideration, the varying standards for cookware that exist from country to country present non-tariff barriers to international trade. Accordingly, there is a need to establish internationally accepted methods of testing cookware for lead and cadmium release, and to de
12、fine permissible limits for the extraction of these toxic metals. An expert panel convened by the World Health Organization (WHO) met (with IS0 participation) in Geneva, in November 1979, and recommended limits for the release of toxic materials from ceramic cookware for a proposed hot test method.
13、Further, the meeting directed that the proposed method be further studied to determine its repeatability and reproducibility. The method specified in this part of IS0 8391 is based on the WHO recommendations and subsequent collaborative studies in which 14 laboratories throughout the USA, Europe and
14、 Japan participated. IS0 8391 consists of the following parts : Part 1 : Method of test. Part 2 : Permissible limits. 1 Scope This part of IS0 8991 specifies a method of test for the release of lead and cadmium by ceramic cookware intended for use in contact with food. 2 Field of application This pa
15、rt of IS0 8391 is applicable to ceramic cookware intended to be used for the preparation of foods by heating. 3 References IS0 3565, Glass plant, pipeline and fittings - Properties of borosilicate glass 3.3. IS0 6955, Analytical spectroscopic methods - Flame emission, atomic absorption and atomic fl
16、uorescence - Vocabulary. 4 Definitions For the purpose of this part of IS0 8391, the following definitions apply. 4.1 ceramic cookware : Ceramic articles which are intended to be heated in the preparation of foodstuffs, for example china, porcelain and earthenware, but excludes glass, glass ceramic
17、and porcelain enamel articles. 4.2 extraction solution : The solvent used in the test to extract lead and cadmium from cookware. 5 Principle Extraction of lead and cadmium by a hot acetic acid solution from the cookware surfaces that would normally come in contact with food and its vapours during co
18、oking. 6 Reagents All reagents shall be of recognized analytical grade. Unless otherwise stated, distilled water or water of equivalent purity shall be used throughout. 6.1 Acetic acid (CH-JOOH), glacial, e = I,06 g/ml. Store this reagent in the dark. 6.2 Extraction solution : acetic acid, 4 % (V/k
19、) solution. Add 46 ml of the glacial acetic acid (6.1) to water and dilute to 1 000 ml. This solution shall be freshly prepared for use. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04
20、/27/2007 21:54:21 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 8391/l-1986 (El 6.3 Stock standard solutions. Prepare stock standard solutions containing 1 000 mg of lead per litre and at least 500 mg of cadmium per litre in the acetic acid solution (6.2) or in a 2 %
21、(V/v) nitric acid solution. Alternatively, appropriate, commercially available lead and cad- mium AAS standard solutions may be used. 7 Apparatus Laboratory glassware shall comply with the requirements of the appropriate International Standards, wherever such Inter- national Standards exist. It shal
22、l be made of borosilicate glass, as specified in IS0 3585. Usual laboratory apparatus, and in particular Atomic absorption spectrometer, having a minimum sen- sitivity of 050 mg of lead per litre, and 0,05 mg of cadmium per litre, for 1 % absorption. It shall be operated in accordance with the manuf
23、acturer s instructions. A digital concentration reader (DCR) attachment is optional, but is useful for rapid analysis. 8 Sampling 8.1 Sample size It is desirable to develop a system of control that is regarded as appropriate to the circumstances. If available, six articles shall be tested. Each of t
24、he articles shall be identical in size, shape, colour and decoration. 8.2 Preparation and preservation of test samples Samples of cookware shall be clean and free from grease or other matter likely to affect the test. Briefly wash the specimens at a temperature of about 40 OC with a solution contain
25、ing a non-acidic detergent. Rinse in tap water and then in distilled water or water of equivalent purity. Drain, and dry in either a drying oven or by means of a new filter paper so as to avoid any stains. Do not handle the sur- faces to be tested after cleaning. 9 Procedure 9.1 Filling volume Deter
26、mine the effective volume of the sample by measuring the volume of water necessary to fill each vessel to the rim. Fill each vessel (cleaned as in 8.3) to two-thirds of its effective volume with water. Then cover the vessels with their own lids. If the cookware vessels under test do not have lids, c
27、over them with flat, opaque, unleaded glass (or other suitable cover) to prevent evaporation and to prevent the surface under test from being exposed to light. 9.2 Extraction Place each vessel on a hotplate and heat the water to a simmer (slow boil) at which time add enough glacial acid (6.1) to pro
28、- duce a 4 % (V/ k I acetic acid solution. The volume, k , of acetic acid required may be calculated from the equation vs = 0,041 VW where V, is the volume of water in the cookware vessel. For vessels possessing their own heating element, the temperature shall be maintained at simmer (slow boil) usi
29、ng that vessel s heating element. In the event that the heating el- ement produces vigorous boiling, a Variac 1) (or similar device) may be used to control the temperature to a simmer. Should the heating element not produce a temperature high enough to simmer the solvent, then the highest temperatur
30、e attainable by the heating element shall be employed. Maintain slow boil or maximum heat attainable, as appropriate, for 2 h commencing from the time of addition of acetic acid. If during the 2 h heating period a loss of solvent occurs (as for example with teapots), replace the loss with preheated
31、acetic acid solution (6.2) to maintain the level of solution at two-thirds of the vessel s effective volume. At the end of the 2 h heating period, remove the heat source promptly. 9.3 Sampling of the extraction solution for analysis Prior to sampling the extraction solution to determine the lead and
32、/or cadmium concentration, mix the extraction solution of each specimen by an appropriate method which avoids any loss of extraction solution or any abrasion of the surface being tested (for example, using a pipette, remove and allow the ex- traction solution to run back on to, and into, the specime
33、n several times). Do not dilute the extraction solution (for example by rinsing the specimen). Transfer the extraction sol- ution to a suitable storage container made of borosilicate glass. It is not necessary to transfer all the extraction solution. If the concentration of the extraction solution i
34、s found to be higher than 20 mg/l, take a suitable aliquot portion and dilute it with acetic acid (6.2) to reduce the concentration to less than 20 mg/l. 1) This trade name for a commercially available product IS given tor the convenience of the user of this part of IS0 8391 and does not constitute
35、an endorsement of the product by ISO. 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 21:54:21 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 839
36、1/l-1686 (E) Analyse the extraction solution as soon as possible after it at- tains room temperature as there is a risk of adsorption of lead or cadmium on to the walls of the storage container, particularly when the metals are present in low concentrations. 9.4 Calibration and determination Establi
37、sh and carefully standardize instrument operating tech- niques so as to utilize maximum sensitivity, as determinations of lead concentrations as low as 050 mg/l, or cadmium con- centrations as low as 0,05 mg/l, require the full potential of most instruments. Prepare calibration solutions by diluting
38、 the stock standard sol- utions (6.3) with acetic acid (6.21, and use the bracketing tech- nique or construct a calibration graph having, for example, the absorbances of the calibration solutions as abscissae, and the corresponding lead or cadmium contents, in milligrams per litre, as ordinates. Car
39、ry out a blank test on the reagents used for each set of determinations. The blank test solution may be used as a zero number for the calibration if the calibration graph technique is used. Alternatively, calibration solutions of higher concentration may be used. Similar considerations apply to the
40、determination of cadmium. Determine the lead and cadmium contents of the extraction solution by atomic absorption spectrometry using the pro- cedure specified by the instrument manufacturer. 10 Expression of results 10.1 Bracketing technique (see IS0 6955, “Determi- nation by the bracketing techniqu
41、e”) The lead or cadmium content, co, expressed in milligrams per litre of the extraction solution, is given by the formula A0 - Al AZ - Al x (c* - c,) + Cl where A0 is the absorbance of the lead or cadmium in the extrac- tion solution; 12 Test report The test report shall include the following infor
42、mation : Al is the absorbance of the lead or cadmium in the lower bracketing solution; a) a reference to this part of IS0 6391; A2 is the absorbance of the lead or cadmium in the upper bracketing solution; b) identification of the sample; c) the results and the form in which these are expressed; cl
43、is the lead or cadmium content, expressed in milligrams per litre, of the lower bracketing solution; d) any unusual features noted during the determination; c2 is the lead or cadmium content, expressed in milligrams e) any operation not included in this part of IS0 6391, or per litre, of the upper b
44、racketing solution. regarded as optional. NOTE - If the extraction was diluted (see 9.5). an appropriate correc- tion factor has to be used in the fdrmula. 10.2 Calibration graph technique Read the lead or cadmium content directly from the calibration curve or from the direct read-out. 10.3 Reportin
45、g Report the results to the nearest 0,l mg of lead per litre and to the nearest 0,Ol mg of cadmium per litre. 11 Precision Table11 I Range or level Repeatability, Reproducibility, tmg/l) r R Lead 0.48 Cpb I.93 Cadmium 0 CC-, 0.10 0,69 I,63 0,Ol 0.01 1) The precision data were obtained from a collabo
46、rative study con- ducted in 1981 by the US Food and Drug Administration. The study in- volved 14 laboratories in the USA, Puerto Rico, Japan, Germany, F.R., Israel, United Kingdom, Ireland, Canada and the Netherlands. The test specimens were found to contain a mean level of I,0 mg/l lead. No cadmium
47、 was present. 11.1 Repeatability The difference between two single results found on identical test material by one analyst using the same apparatus within a short time interval will exceed the repeatability given in the table on average not more than once in 20 cases in the normal and correct operat
48、ion of the method. 11.2 Reproducibility The difference between two single and independent results found by two operators working in different laboratories on identical test material will exceed the reproducibility given in the table on average not more than once in 20 cases in the normal and correct
49、 operation of the method. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 21:54:21 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 8391/l-1986 (E) Bibliography Ill Proceedings, International Conference on Ceramic Foodware Safety,